Google’s Big Panda is that any Website that just has “quality content” is begging to be ignored in the search results, overlooked in the indexing, bypassed in the linking, and otherwise obstructed from propelling its owners and masters to the heights of AdSense-funded financial success.

Hi,
Google Panda is just another name given to the Google's Algorithm which is responsible to decide the Page Rank and SERP ranking of a website in the Google's search results in a search term. You can get more information regarding this topic on the web.

For anyone who still does not know what Google Panda is, it is the name given to a change to their algorithm which was launched in February 2011 with the purpose of "Finding more high-quality sites in search".
If you would like to read some of what Google has to say about it, please follow these links to official statements, which are in chronological order: